You can set a pot in the ground and then dig, cut roots and bring in for winter. These plants can tolerate having their roots cut. For now remove the current pot and repot in a larger container, cutting roots if needed to make it fit. Then water and keep the soil moist, not soggy while it establishes roots. You can plant it outdoors on another couple of weeks in its new home. Fertilize with a soluble plant food monthly. Or you can apply a granular product applying a half cup  in a 6 foot diameter area around the plant (to 3' out from trunk on all sides). Scratch it into the soil surface if possible and water it in well. Make the granular fertilizer application a week after planting and again in mid summer.